In the past mortise and tenon joint members have been cut using a variety of methods and devices.
Mortises have been cut using plunge type routers controlled by numerous guiding systems, including standard router fence guides, router template guide bushes, and fences for router bases. Anything that provides a straight edge, or guide, or edges on which the router bush, base edge or fence guide can run is suitable. Groves U.S. Pat. No. 4,197,887 and Hounshell U.S. Pat. No. 4,763,707 disclose a router base arrangement having two projecting pins, one either side of the router cutter, to allow for automatic centering of a mortise to be cut in a workpiece.
In the case of tenons, applicant's Peterson U.S. Pat. No(s). 4,428,408 and 4,479,523 both disclose jigs that permit two step routing of tenons. Peterson requires turning the jig template on the workpiece while applicant's patent requires turning the workpiece and template. Applicant's previous patent allows for easy routing of square cornered tenons having the thickness of the workpiece but the matching mortises must be hand squared.
As far as applicant is aware, a method or apparatus which allows for single pass routing of radiused tenons and corresponding radiused mortises using only a hand held portable router has not yet been developed. At present, the only way radiused cornered tenons can be made on one pass is with a stylus guided copy router type machine where the router is carried on an XY axis and guided by a separate pin or roller around a fixed tenon shape. These involve considerably higher cost machines such as those disclosed in Wirth U.S. Pat. No. 4,593,735 and Ducate U.S. Pat. No. 4,749,013.